Is this underlying cause of rising inequality?

From David Brooks' Atlantic article,

If you want to summarize the changes in family structure over the past century, the truest thing to say is this: We’ve made life freer for individuals and more unstable for families. We’ve made life better for adults but worse for children. We’ve moved from big, interconnected, and extended families, which helped protect the most vulnerable people in society from the shocks of life, to smaller, detached nuclear families (a married couple and their children), which give the most privileged people in society room to maximize their talents and expand their options. The shift from bigger and interconnected extended families to smaller and detached nuclear families ultimately led to a familial system that liberates the rich and ravages the working-class and the poor.

Seems to explain the increase in inequality that economists have attributed to a variety of factors like assortive mating (educated individuals marrying each other) or education (huge returns to education, which increases intergenerational stickiness between income deciles)

Finally, over the past two generations, families have grown more unequal. America now has two entirely different family regimes. Among the highly educated, family patterns are almost as stable as they were in the 1950s; among the less fortunate, family life is often utter chaos.